The invention relates generally to methods and system for reconstruction of computed tomography (CT) images, and more particularly to methods and system for correcting detector open cell errors.
In various known computed tomography (CT) imaging system configurations, an X-ray source in a CT scanner, projects a fan-shaped beam that passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the X-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are used to reconstruct the image of the scanned object.
With the development of volumetric CT (VCT) scanner, the number of detectors in the scanner is increasing rapidly. Various known VCT scanners contain up to sixty four detector rows in which nearly 64000 detector cells are present for each detector. As a result, the probability of a detector channel failure increases.
Known techniques of dealing with a failed detector channel include replacement of the failed detector channel. However, replacement of failed detector channels leads to a significant increase in the cost of medical imaging systems and the downtime of the clinical operation of scanning a patient.
In addition, with the increasing number of detector channels contained in a CT scanner, it is not economical to replace all the failed detector channels. Various known techniques that determine and correct for failed detector channels are inadequate with some detector failure modes, such as detector open cell error. A detector open cell error occurs when a detector cell looses contact with the neighboring detector cells. The known techniques for image reconstruction produce images with severe artifacts caused due to some detector failure modes, such as detector open cell error.